Provided are: a conductive paste in which sinterability of silver particles the conductive paste can be easily controlled by using silver particles having predetermined crystal transformation characteristics defined by an XRD analysis, and after a sintering treatment, excellent electrical conductivity and thermal conductivity can be stably obtained; and a die bonding method using the conductive paste.Disclosed is a conductive paste which includes silver particles having a volume average particle size of 0.1 to 30 μm as a sinterable conductive material, and a dispersing medium for making a paste-like form, and in which when the integrated intensity of the peak at 2θ=38°±0.2° in the X-ray diffraction chart obtainable by an XRD analysis before a sintering treatment of the silver particles is designated as S1, and the integrated intensity of the peak at 2θ=38°±0.2° in the X-ray diffraction chart obtainable by an XRD analysis after a sintering treatment (250° C., 60 minutes) of the silver particles is designated as S2, the value of S2/S1 is adjusted to a value within the range of 0.2 to 0.8.
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1. A conductive paste comprising silver particles having a volume average particle size of 0.1 to 30 μm as a sinterable conductive material, and a dispersing medium for making a paste, wherein when the integrated intensity of the peak at 2θ=38°±0.2° in the X-ray diffraction chart obtainable by an XRD analysis before a sintering treatment of the silver particles is designated as S1, and the integrated intensity of the peak at 2θ=38°±0.2° in the X-ray diffraction chart obtainable by an XRD analysis after a sintering treatment, at 250° C. for 60 minutes, of the silver particles is designated as S2, the value of S2/S1 is adjusted to a value within the range of 0.2 to 0.8, and the amount of incorporation of the dispersing medium is adjusted to a value within the range of 5 to 30 parts by weight relative to 100 parts by weight of the silver particles.
A conductive paste for die bonding contains silver particles (0.1 to 30 μm in size) that can be sintered. A dispersing medium is added to make the paste workable. The paste's silver particles are analyzed using X-ray diffraction (XRD) before and after a sintering process (250°C for 60 minutes). Before sintering, the XRD peak intensity at 2θ=38°±0.2° is S1. After sintering, the same peak's intensity is S2. The ratio S2/S1 is between 0.2 and 0.8. The dispersing medium makes up 5 to 30 parts by weight for every 100 parts of silver particles. This composition provides stable electrical and thermal conductivity after sintering, useful in die bonding applications.
2. The conductive paste according to claim 1 , wherein when the peak height of the peak at 2θ=38°±0.2° in the X-ray diffraction chart obtainable by an XRD analysis before a sintering treatment of the silver particles is designated as L1, and the peak height of the peak at 2θ=38°±0.2° in the X-ray diffraction chart obtainable by an XRD analysis after a sintering treatment, at 250° C. for 60 minutes, of the silver particles is designated as L2, the value of L2/L1 is adjusted to a value within the range of 0.5 to 1.5.
This conductive paste is the same as the paste containing silver particles (0.1 to 30 μm in size) that can be sintered, with a dispersing medium to make it workable, where the silver particles are analyzed using X-ray diffraction (XRD) before and after a sintering process (250°C for 60 minutes), giving peak intensities S1 and S2 with a ratio S2/S1 between 0.2 and 0.8, and the dispersing medium making up 5 to 30 parts by weight for every 100 parts of silver particles. In addition, the height of the XRD peak at 2θ=38°±0.2° is measured before sintering (L1) and after sintering (L2). The ratio L2/L1 is between 0.5 and 1.5. This relates to the silver particle's crystal transformation characteristics.
3. The conductive paste according to claim 1 , wherein when the full width at half maximum of the peak at 2θ=38°±0.2° in the X-ray diffraction chart obtainable by an XRD analysis before a sintering treatment of the silver particles is designated as W1, and the full width at half maximum of the peak at 2θ=38°±0.2° in the X-ray diffraction chart obtainable by the analysis after a sintering treatment, at 250° C. for 60 minutes, of the silver particles is designated as W2, the value of W2/W1 is adjusted to a value within the range of 0.3 to 0.9.
This conductive paste is the same as the paste containing silver particles (0.1 to 30 μm in size) that can be sintered, with a dispersing medium to make it workable, where the silver particles are analyzed using X-ray diffraction (XRD) before and after a sintering process (250°C for 60 minutes), giving peak intensities S1 and S2 with a ratio S2/S1 between 0.2 and 0.8, and the dispersing medium making up 5 to 30 parts by weight for every 100 parts of silver particles. Furthermore, the full width at half maximum (FWHM) of the XRD peak at 2θ=38°±0.2° is measured before sintering (W1) and after sintering (W2). The ratio W2/W1 is between 0.3 and 0.9. This controls the sinterability of the paste.
4. The conductive paste according to claim 1 , wherein the silver particles are hollow silver particles.
This conductive paste is the same as the paste containing silver particles (0.1 to 30 μm in size) that can be sintered, with a dispersing medium to make it workable, where the silver particles are analyzed using X-ray diffraction (XRD) before and after a sintering process (250°C for 60 minutes), giving peak intensities S1 and S2 with a ratio S2/S1 between 0.2 and 0.8, and the dispersing medium making up 5 to 30 parts by weight for every 100 parts of silver particles. In this version, the silver particles are hollow. The hollow structure affects the sintering process and the final conductivity.
5. The conductive paste according to claim 1 , wherein the surface of the silver particles is covered by at least one organic surface treating agent selected from an organic acid, an organic acid salt, a surfactant, and a coupling agent.
This conductive paste is the same as the paste containing silver particles (0.1 to 30 μm in size) that can be sintered, with a dispersing medium to make it workable, where the silver particles are analyzed using X-ray diffraction (XRD) before and after a sintering process (250°C for 60 minutes), giving peak intensities S1 and S2 with a ratio S2/S1 between 0.2 and 0.8, and the dispersing medium making up 5 to 30 parts by weight for every 100 parts of silver particles. Furthermore, the surface of the silver particles is coated with an organic surface treatment agent. This agent can be an organic acid, an organic acid salt, a surfactant, or a coupling agent. This coating modifies the surface properties, influencing dispersion and bonding.
6. The conductive paste according to claim 1 , wherein the dispersing medium is at least one compound selected from the group consisting of a glycol ether-based compound, a glycol ester-based compound, a hydrocarbon-based compound, and a polar solvent.
This conductive paste is the same as the paste containing silver particles (0.1 to 30 μm in size) that can be sintered, with a dispersing medium to make it workable, where the silver particles are analyzed using X-ray diffraction (XRD) before and after a sintering process (250°C for 60 minutes), giving peak intensities S1 and S2 with a ratio S2/S1 between 0.2 and 0.8, and the dispersing medium making up 5 to 30 parts by weight for every 100 parts of silver particles. In this version, the dispersing medium is a glycol ether-based compound, a glycol ester-based compound, a hydrocarbon-based compound, or a polar solvent. The choice of dispersing medium affects paste viscosity and silver particle dispersion.
7. The conductive paste according to claim 1 , wherein the conductive paste further comprises an organic compound, and the amount of incorporation of the organic compound is adjusted to a value within the range of 0.5 to 10 parts by weight relative to 100 parts by weight of the silver particles.
This conductive paste is the same as the paste containing silver particles (0.1 to 30 μm in size) that can be sintered, with a dispersing medium to make it workable, where the silver particles are analyzed using X-ray diffraction (XRD) before and after a sintering process (250°C for 60 minutes), giving peak intensities S1 and S2 with a ratio S2/S1 between 0.2 and 0.8, and the dispersing medium making up 5 to 30 parts by weight for every 100 parts of silver particles. In addition, the paste includes an organic compound. The amount of this organic compound is between 0.5 and 10 parts by weight for every 100 parts of silver particles. This organic compound can influence sintering behavior or final bond strength.
8. The conductive paste according to claim 7 , wherein the organic compound is a thermosetting resin including at least one of an epoxy resin and a phenolic resin.
This conductive paste is the same as the paste containing silver particles (0.1 to 30 μm in size) that can be sintered, with a dispersing medium to make it workable, where the silver particles are analyzed using X-ray diffraction (XRD) before and after a sintering process (250°C for 60 minutes), giving peak intensities S1 and S2 with a ratio S2/S1 between 0.2 and 0.8, and the dispersing medium making up 5 to 30 parts by weight for every 100 parts of silver particles, and also containing an organic compound, where the amount of this organic compound is between 0.5 and 10 parts by weight for every 100 parts of silver particles. Here, the organic compound is a thermosetting resin. This resin can be an epoxy resin or a phenolic resin. The thermosetting resin improves the mechanical properties and adhesion of the sintered paste.
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August 20, 2013
November 14, 2017
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